【Paper】
Dechlorination of Trichloroethylene by the Solvothermal Process
Hirofumi Ikeda*, Masaya Urakami*, Kei Sasabe*, Yoshinori Miyamoto* and Nakamichi Yamasaki**
* Kimura Chemical Plants Co., Ltd.
** Graduate School of Environmental Studies, Tohoku University
† Correspondence should be addressed to Hirofumi Ikeda:
Kimura Chemical Plants Co., Ltd.
（2-1-2 Terajima, Kuise, Amagasaki-shi, Hyogo, 660-8567 Japan）

Abstract
Many kinds of processes for the removal and decomposition for trichloroethylene（TCE）have been investigated. The solvothermal process using methanol and sodium hydroxide（alkaline methanol solvent）has been developed and compared with ordinary alkaline hydrothermal conditions for dechlorination of TCE.
Even under alkaline hydrothermal condition using water as a solvent, perfect dechlorination of TCE（initial concentration up to 42,000mg/L）is achieved at a reaction temperature of 523K and a few minutes of reaction time if the ratio of used NaOH to required NaOH is greater than 2.0. However, polymers are formed as byproducts and secondary disposal of solvents is required, because whole dissociated chloride ions are dissolved in the solvent. In contrast, we found that dechlorination of TCE（initial concentration 82,000mg/L）is possible with a reaction temperature of 523K and a reaction time of 15 minutes by using thermal alkaline methanol solvent. Furthermore, the solvent（methanol）can be reused easily after the separation of sodium salts, because the dissociated chloride precipitates with salts and are not dissolved in methanol. Therefore, the dechlorination process of TCE can be made simpler and the secondary disposal of wastewater is not required.

Key words: alkaline methanol, alkaline hydrothermal solvent, solvothermal process, dechlorination, trichloroethylene